Air conditioning unit



Dec. 6, 1960 w. MOGRATH 2,962,952

' AIR CONDITIONING UNIT Filed March 1. 1957 2 Sheets-Sheet 1 F I G. I

IN VEN TOR.

WILLIAM L. McGRATH.

BY WJM ATTORNEY Dec. 6, 1960 Filed March 1, 1957 www- W. L. M GRATH AIRCONDITIONING UNIT 2 Sheets-Sheet 2 INVENTOR. WILLIAM L. McGRATH.

WJM

ATTORNEY;

AIR CONDITIONING UNIT William L. McGrath, Syracuse, N.Y., assignor to,Carrier Corporation, Syracuse, N.Y.,'a -corporatiou of Delaware FiledMar. 1, 1957, Ser. No. 643,427 4 Claims. (C l. 98-38) This inventionrelates to air conditioning units and more particularly to improved airconditioning units containing slot type primary air discharge means andmeans to act therewith to induce a stream of secondary air from the areabeing conditioned through a heat exchange member in the unit and toefiiciently and quietly 'mix with the stream of primary air, the mixtureof primary air and secondary air being discharged within the area beingtreated.

In Carrier Patent No. 2,363,294, granted November 21, 1944, there isdisclosed an air conditioning system for multi-room buildings whichcontemplates a supply of conditioned air from a central station at highvelocity and static pressure through small conduits to room units placedin the rooms being conditioned. Each room unit.

includes a heat exchanger through which cold or hot water may be passed,depending upon temperature conditions exteriorly of the building. Astream of conditioned primary air (cold or warm) from the centralstationv is discharged into the unit at a velocity such as to induce astream of secondary air from the room into the unit through the heatexchanger to mix therewith. The mixture of streams is then dischargedinto the room to cool or heat the same.

The system disclosed in the Carrier patent has been acknowledged as themost commercially desirable system available. Owners of buildings suchas hotels, office build I ings, etc., have also recognized the superiorresults obtainable from the Carrier system and insist on the use of suchsystem in their buildings when superior results are desired.

The extensive use of glass in buildings has robbed these buildings ofinsulation and caused large transmission losses for which these unitsmust compensate. Not only have these glass windows increased the load,but they have also come closer to the floor level, further decreasingthe space available for the unit itself. Present day units, therefore,must be small and highly effective.

In meeting these requirements, the unit should be fabatent' comprises acasing having a plenum member therein, said plenum member beingconnected to a source of primary air. Air discharge means are connectedto the plenum; a heat exchange member adapted to be connected to asource of heat exchange medium is located within the unit, the dischargemeans of the primary air being of a slot type to induce a stream ofsecondary air from the area being conditioned through the heat exchangemember into heat exchange relation with medium passing therethrough tomix with the primary air being discharged from the slot nozzle andconduit means for passing the air through the primary air stream so thatan induction ettectwill take place on both sides of the slot nozzle.

The attached drawings. illustrate a preferred embodiment of my inventionin which:

Figure l is a perspective view of an air conditioning unit of theinvention installed in a room being conditioned;

Figure 2 is a sectional view taken from the side of the unit;

Figure 3 is a sectional view taken from the front of the unit;

Figure 4 is a fragmentary view of the slot type nozzle utilizing thepresent invention; and

Figure 5 is a plan view of a modification of the inven tion shown inFigure 4.

Referring to the attached drawings, there is shown in Figure 1 an airconditioning unit 1 placed beneath the window of a room being treated.

casing 2 in which there are located a discharge opening '4 and an inletopening 3. These openings each consist of a series of louvered openingsthrough which a stream ricated at a minimum cost so as to render the useof this system competitive with other systems. One of the suggestedsolutions to this cost problem resides in the use of an inexpensive slottype nozzle in the units. It has been found, however, that at the highpressures customarily employed, the slot type nozzle is prohibitivelynoisy and unsatisfactory.

The chief object of the present invention is to provide an improved lowcost induction unit for air conditioning systems.

An object of the invention is to provide an inexpensive high capacityunit capable of operating at low noise levels.

A still further object is to provide a low'noise level induction unit,utilizing high pressure primary air discharged through slot type nozzleslocated within the unit. Other objects of my invention will be readilyperceived from the following description;

This invention relates to an air conditioning unit for usein the airconditioning ofmulti-room buildings which of secondary air is inducedinto the unit and a mixture of primary and secondary air is dischargedfrom said unit. There is located adjacent the opening 3 a heat exchangemember 10 more fully described hereinafter.

A plenum 5 is located at the bottom portion of the casing 2 and itconsists of an elongated chamber extending the length of the casing,being suitably insulated by material 7 and having an air inlet 6 throughwhich primary air is passed into the plenum. This primary air originatesat a central station (not shown); is passed into the plenum from whenceit is discharged through the nozzle 8 into' the unit.

The nozzle 8 consists of an elongated slot through which air is passedto the chamber above the plenum. As the air passes through the nozzle,secondary air is drawn in from the room through the opening 3 thenthrough the heat exchange member 10. The primary and secondary airstreams are then mixed.

Slot type nozzles have been previously used in low pressure airconditioning systems. In these particular systems the pressure of theprimary air was suificiently low as not to raise any serious noiseproblems. However, with the diminishing amount of space allotted to theinduction unit as previously outlined, it has become extremely necessarythat the air quantities and the amount of heat exchange handled by theinduction unit be substantially increased. This problem has beenpartially solved by improved heat exchangers; however, with theincreased pressures utilized in these particular units, the noise levelhas also increased to a point where slot type nozzles have becomeunsatisfactory in operation and there has been a marked departure fromthe use of nozzles of the Small circular nozzle openings have foundfavor because of their more stable operation and because theyprovide-much lower noise levels in operation. However, this type nozzleis more expensive when it is realized that production thereof entailsthe drilling of hundreds of small holes into a nozzle sheet.

Before the trend to small circular openings in nozzles,

Patented Dec. 6, 1960 air passing:therethroughn It is extremelyimportant-that the cdgesof-the slot-be precise 'and uniform andthat auniformtidistauce betweenthese edges extend the entire] length: of thenozzle. Itis believed thatthe increase in noise level of the slot'nozzle'is at -leastpartly due torthe transverse'instability of the airstream.- For-example: in

a long-slot there areno longitudinal means to direct'the air stream. 1As the air enters the plenum there is a component of air velocity in adirection-longitudinal*to the;-' slot which is present'in'the airas 'itpasses through the nozzle.

it passes through-the nozzle "which creates' a plurality of eddies-orvortices which arecapableof moving transversely, resulting in adistinctive noise: t Should the particular nozzle length-be in'some waytuned to a particular frequency, a deep hum may also result in theoperation of the unit.

Figure 4 illustrates a type of nozzle contemplated for the presentunitfor the purpose of controlling the previously mentioned eddies witha resulting decrease in the noise level of the unit. In this figurethere is shown an opening 21which constitutes the nozzle in nozzle sheet20; this opening is created by upwardly bent lips 22 and 23 which tendto converge. The edge of the lipsmay be provided with either a sawtoothedgeor an undulating edge; the tips of the edge may be bent inwardly.The

Because of this lack of directingmeans 'in the nozzle there is aninherent instability of the air stream as purpose of such a constructionis toprovide an'unevenness in the slot opening in such a manner as tocontrol the size and location of the eddies which are normally formedduring the operation of a slot type nozzle.

Figure 5 shows a modificationof the nozzle construction illustrated inFigure 4. This figure illustrates a slot type'nozzle formed in a singleplane in a nozzle sheet 31. This nozzle is in the shape of an irregularslot formed by the undulating edges 33 and 34. These edges have'highpoints 36 and 37 which are'dire'ctly opposite on the sides of the nozzleopening. By such a construction a similar effect is derived as isacquired from the construction shown in Figure 4. By this type ofconstruction the eddies are positively determined by the increase anddecrease of the slot opening. By controlling the size and also thelocation of these eddies substantiallyquiet operation is obtained fromthe induction unit.

Located above the plenum between the opening 3 and the nozzle 8 is aheat exchange member 10 which comprises a plurality of parallel extendedfin members having a general trapezoidal shape. At the end of the heatexchange member adjacent to nozzle 8 the heat exchange fin members 11have their greatest area. However, as the distance from the nozzleincreases the surface area of the fin members decreases. A plurality oftubes 12 are shown which are connected into a single circuit throughwhich heat exchange medium is passed. The fins 11 are attached to thesetubes and act as an extended surface therefor. The aforementioned heatexchange medium originates from a central station of the airconditioning system and may consist of either hot or cold water.

As the air is discharged from the nozzle 8, secondary air is inducedthrough the opening 3 from the room. This secondary air because of theextended surface of the heat exchange member 10 is placed into heatexchange relation with the medium passing through the tubes 12. Thetreated air then mixes'with the primary air discharged from the nozzle 8and themixture is then discharged through the outlet 4 of the unit intothe room.

Referring to Figure 2, it will be noted that as the secondary air passesinto the unit there is a tendency for the secondary air, after it passesthrough the heat exchange member 10, to mix with the primary air issuingfromthe discharge nozzle 8 on the front side of the nozzle in the areabetween the' nozzle and the heat exchange member 10. There is alsocreated a low pressure area on the back side of the nozzle between thenozzle and the wall 9. The inefliciencybf such a construction isobvious. Air enters the unit and mixes on the front side of the nozzle;however, the rear section of the nozzle is isolated so as to be unableto participate in the induction and mixing effect with the secondaryair.

In order to morefully use the capacity potential of slot type nozzle,the presentinvention envisions the use of 'a plurality of censure; '13passing through the primary air stream; thereby putting 'the rearsection of the nozzle 8 into communication with the air passing throughthe opening 3 and the heat"exchang'e member 10.

In Figure 3, there is shown a sectional view of the unit indicating thefro'rit 'ofthe unit minus the heat exchange member 10. This viewillustrates that the plenum extends the entire length of the unit and issubstantially covered with insulatingmaterial. The'prim'ary air supplyduct'is connected to the centralstation of the air conditioning systemfrom whence primary air is passed to the plenum 5 of the unit. The airleaves the plenum 5 through the longitudinal slot nozzle 8, passesupwardly about the conduit members 13, 14 and 15, and is confined by thebaffiemembers 16 and 17 and discharged from the unit through thedischarge opening 4.

This particular figure illustrates the nature of conduits 13, 14 and 15;It will benoted thatthese conduits'have a streamlined shape," verysimilar to a teardrop in crosssection." This type of construction hasbeen found to offer the least amount of resistance to the primary airflow. As can be seen, the air which is discharged through the nozzlepasses upwardly and these conduits are in the dir'ec'tp'ath of the airstream. By suitable sizing and shaping'these conduits, a minimum amountof resistance is provided to'impede the primary air stream. Furthermore,this shape permits conduits of adequate size so as to permit asubstantial amount of air to pass through the inlet 3, heat exchanger 10and through the conduits to the rear section of the nozzle 8 where asubstantial induction and mixing effect is acquired.

In order to obtain uniform air flow through the heat exchange member 10,the fin members 11 of the heat exchange member have a generaltrapezoidal shape as previously mentioned. This provides a path of airthrough the heat exchange member of decreasing resistwice to saidsecondary air stream as it passes therethrough. This particularconstruction is provided to compensate for "the decrease in inductiveeffect as the distance from the nozzle 8 increases. Adjacent to nozzle 8the inductive effect is high; however, at the upper part of the heatexchange member 10, this effect reaches a minimum. To compensate forthis and to make more efficient use of the heat exchange member, thetrapezoidal fin member preferably is incorporated into this particularplate fin coil. The construction illustrated by being able to make useof the front and rear sections'of the primary air stream issuing fromthe plenum creates a greater inductive effect than can normally beacquired by the single side of the air stream. This also permits the useof a deeper heat exchange member which is a direct result of theincreased inductive effect acquired by the use of the rear portion ofthe primary air stream.

It will be noted that from the previous description there has been shownan induction unit capable of makinguse of a slot type nozzle which is anextremely economical item to manufacture compared with similar nozzleconstructions requiring the drilling of hundreds of circular holes in asingle nozzle sheet, or in some casesthe molding of plastic nozzleclusters having a plurality of nozzle openings oriented in such a manneras to make necessary a diflicult manufacturing process. The slot typenozzle is extremely easy to manufacture and the type herein employeddoes not require minute clearances normally necessary; The use ofserrations or undulations permits variances in manufacturing processwhich will not result in any subsequent noisy operation of the unit.

While I have described a preferred embodiment of the invention, it willbe understood that the invention is not limited thereto, since it may beotherwise embodied within the scope of the appended claims.

I claim:

1. In an air conditioning unit, the combination of a casing, a plenummember placed in said casing, means defining an outlet in said casing,means defining an inlet in said casing, said plenum being connected to asource of primary air, a nozzle member having an elongated slot thereinassociated with said plenum and extending substantially parallel to saidinlet whereby the discharge of primary air through said slot induces astream of secondary air through the inlet to mix with the primary airbeing discharged from the plenum, and hollow, conduit means placed abovethe slot in the unit forming passages for secondary air from the frontof the unit rearwardly over the slot so that said secondary air may beinduced into the primary air stream at the rear por- 'tion of saidnozzle member.

2. An air conditioning unit according to claim 1, in which the conduitmeans has a general teardrop crosssection.

3. An air conditioning unit according to claim 2 in which the nozzlemember forms an elongated slot having edges having a substantialsawtooth configuration.

4. An air conditioning unit according to claim 2, in which the edges ofthe nozzle slot are undulating.

References Cited in the file of this patent UNITED STATES PATENTS612,480 Stevens Mar. 21, 1899 2,122,168 Woolley June 28, 1938 2,140,305Ashley et a1. Dec. 13, 1938 2,287,267 Palmer June 23, 1942 2,345,536Keep Mar. 28, 1944 2,567,758 Ashley Sept. 11, 1951 2,778,688 Carl Jan.22, 1957 2,783,979 Blum Mar. 5, 1957 2,854,915 Carr Oct. 7, 1958 FOREIGNPATENTS 705,873 Great Britain Mar. 17, 1954

